SKRR Downshift Techniques & Replacement Tires

[cloudy]

Seems to me (and several people I talked to at the stealership) that there is usually a "lumpy resistance or notchy feel" felt in the clutch pull when downshifting, especially if one touches the shifter at all before pulling in the clutch. According to the owners manual the Shift Assist is only for upshifting, however it seems to work just fine for downshifting with just a very light touch on the throttle at the right time. Anybody have comments or suggestions with regard to using this technique?

I'm also researching replacement tires and wondered if there are any good known alternatives to the Metzler Racetech's the bike came with. Still a little early (1700 miles), but I can see the need coming in the very near future. I don't want to significantly compromise the handling or confuse the electronics, but am wondering if a sport tour compound Conti (have had good luck with the Road Attacks for general use) or something similar might work out OK.

[woolf]

the same can be asked for the HP2 SPORT

[Daytona_Rider]

I wouldn't worry about "confusing the electronics" as the tire or tire compound has zero to do with the bikes decision over whether to cut power or modulate the brakes. It's only the traction or lack of that does so. The computer only senses wheel spin or differentials in wheel speed for example - it has no way of knowing what the "level of traction" a certain tire is going to give. A sport touring tire will be just fine if you plan on that type of riding. The only way you will get into trouble is asking a sport touring tire for more traction than it has to give - the computer can't replace good decision making.

Shift assist doesn't work for downshifts and learning to blip the throttle will absolutely overcome your difficulties with downshifting. Shift assist only kicks in on the upshift side... the computer doesn't recognize the downshift - unless BMW is doing it completely different on the KRR than the HP2 (and I am sure it's the same unit).

[cloudy]

Daytona Rider
Thannks for the reply.
I agree the sport touring tire should work fine within it's limits, as I've been using them successfully on a variety of bikes for years. In general I've found that for the majority of my street riding, including Sunday rides thru the mountains with a few friends at a "rather spirited" pace, one doesn't sacrifice all that much traction versus the pure sporting compounds of the same make. If I had to guess a number, the sport touring tires probably provide 85-90% of the traction the sport compounds offer, which is more than adequate as road conditions (dirt/gravel, etc.) limit speeds far more than outright traction limits. I was really just wondering if anyone has run alternatives on the SKRR yet and what the results were for specific brands. Was only mentioning the "confusing the electronics thing" because I thought I'd read somewhere that BMW didn't recommend different tire profiles (not sizes, but profiles) from OEM due to the fact that the electronics were developed based on that specific tire combination.

After owning and riding at least 20-30 bikes over the last 41 years, I understand how to downshift by matching engine speed to road speed during downshifts. The question I have revolves around the clutch feeling as if it has a tight spot/resistance when pulled in to downshift, which I've so far assumed is either related to the slipper clutch, or the fact that the shift assist is possibly still interfering somewhat if one touches the shift lever prior to clutch disengagement. As I mentioned earlier, I've found that if I just use the shifter to downshift without using the clutch at all, and add just a touch of throttle opening at the proper time (not to really change rpm but just to unload the transmission a bit), downshifts are as seamless, quick, and as silent as upshifts are when using the shift assist.

Normal downshifting techniques I've used for years on every other bike I've ever ridden are bothersome due to the resistance that is often present part way thru the clutch lever travel. It feels like something other than just clutch disengagement is going on many times, with something else introducing a notchy resistance to the clutch lever travel. Time will tell I guess.

[Daytona_Rider]

Originally Posted by cloudy

Daytona Rider
Thannks for the reply.
I agree the sport touring tire should work fine within it's limits, as I've been using them successfully on a variety of bikes for years. In general I've found that for the majority of my street riding, including Sunday rides thru the mountains with a few friends at a "rather spirited" pace, one doesn't sacrifice all that much traction versus the pure sporting compounds of the same make. If I had to guess a number, the sport touring tires probably provide 85-90% of the traction the sport compounds offer, which is more than adequate as road conditions (dirt/gravel, etc.) limit speeds far more than outright traction limits. I was really just wondering if anyone has run alternatives on the SKRR yet and what the results were for specific brands. Was only mentioning the "confusing the electronics thing" because I thought I'd read somewhere that BMW didn't recommend different tire profiles (not sizes, but profiles) from OEM due to the fact that the electronics were developed based on that specific tire combination.

After owning and riding at least 20-30 bikes over the last 41 years, I understand how to downshift by matching engine speed to road speed during downshifts. The question I have revolves around the clutch feeling as if it has a tight spot/resistance when pulled in to downshift, which I've so far assumed is either related to the slipper clutch, or the fact that the shift assist is possibly still interfering somewhat if one touches the shift lever prior to clutch disengagement. As I mentioned earlier, I've found that if I just use the shifter to downshift without using the clutch at all, and add just a touch of throttle opening at the proper time (not to really change rpm but just to unload the transmission a bit), downshifts are as seamless, quick, and as silent as upshifts are when using the shift assist.

Normal downshifting techniques I've used for years on every other bike I've ever ridden are bothersome due to the resistance that is often present part way thru the clutch lever travel. It feels like something other than just clutch disengagement is going on many times, with something else introducing a notchy resistance to the clutch lever travel. Time will tell I guess.

I didn't mean to insult you by suggesting the blipping...

Your problem - if it's resistance whilst pulling in the clutch could be cable related. Maybe the cable could use some lubrication; maybe it wasn't properly OEM? Dunno. I have a CRG GP Clutch perch on my race bike and it really improved the feel of the clutch. Also you can adjust the feel and the pull ratio of the clutch lever so as to make the pull easier and smoother.

Just a thought.

I sure can't see how the slipper clutch would cause this issue, but I'm not a BMW Mechanic by any means. Perhaps you could install a new shifter star and detent arm/spring from Factory Pro - I believe they have kits for the SKRR. They have been said to really improve shifter feel and performance. I know it made a difference in my RC51 Race bike.


Tires and profiles aren't effecting the electronics on any of the race machines I'm familiar with (although that number is only 4 bikes). Guys have been using Pirelli, Michelin, Dunlop, and the OEMs with no change in electronics. I have seen much difference in geometry based upon tire choice.

Personally I really think BMW tells consumers those things to:

A: Keep you buying tires they have in stock.
B: Keep perople from buying tires and not understanding the changes in geometry and resultant handling changes.

I dunno.

Anyway - I hope to hear of you success with this issue.

Cheers

[cloudy]

Originally Posted by Daytona_Rider

I didn't mean to insult you by suggesting the blipping...

Probably took that wrong, but no problem......

Your problem - if it's resistance whilst pulling in the clutch could be cable related. Maybe the cable could use some lubrication; maybe it wasn't properly OEM? Dunno. I have a CRG GP Clutch perch on my race bike and it really improved the feel of the clutch. Also you can adjust the feel and the pull ratio of the clutch lever so as to make the pull easier and smoother.

Will keep these ideas in mind, but the problem only occurs during downshifting. I will check cable lubrication, etc, but doubt that's part of the problem. Clutch pull is silky smooth sitting still or when upshifting w/o shift assist. As I mentioned when I started this thread, the boys at the Stealership noticed this issue with all the SKRR's they've ridden and have no clue either. It feels like I'm hitting a mechanical resistance during clutch disengagement about half way through the lever throw, and has since day 1, not every time, but most times during downshifting. I'll need to confirm with additional testing once I get time, but I believe that it's related to pre-loading (as in just touch it with your toe) the shift lever in the slightest before pulling the clutch lever.

Just a thought.

I sure can't see how the slipper clutch would cause this issue, but I'm not a BMW Mechanic by any means. Perhaps you could install a new shifter star and detent arm/spring from Factory Pro - I believe they have kits for the SKRR. They have been said to really improve shifter feel and performance. I know it made a difference in my RC51 Race bike.

This is worth looking into and appreciate the suggestion.

Tires and profiles aren't effecting the electronics on any of the race machines I'm familiar with (although that number is only 4 bikes). Guys have been using Pirelli, Michelin, Dunlop, and the OEMs with no change in electronics. I have seen much difference in geometry based upon tire choice.

I've been down the profile vs. geometry road before, sometimes with good results and sometimes not. I suspect the good results were due to inadvertently correcting undiagnosed suspension setup problems. My current thinking is to stay with the same size and profile once I see what's available and compare pricing and life expectancy.



Personally I really think BMW tells consumers those things to:

A: Keep you buying tires they have in stock.
B: Keep people from buying tires and not understanding the changes in geometry and resultant handling changes.

Agree wholeheartedly with the above.

I dunno.

Anyway - I hope to hear of you success with this issue.

Cheers

Will post results once I get to the bottom of these issues.

[M5guy]

Originally Posted by cloudy

Seems to me (and several people I talked to at the stealership) that there is usually a "lumpy resistance or notchy feel" felt in the clutch pull when downshifting, especially if one touches the shifter at all before pulling in the clutch. .

The clutch cable does have a notch or click or brief resistance feel to it. Service manager told me this is normal and has to do with a spring in the slipper clutch. I don't notice it now like I did in the first thousand miles.


Steve
10 S1000RR
00 M5

[cloudy]

Thanks M5guy. That's pretty much the gist of what I got from my dealership mechanics too. With 2000+ miles on my bike it's still there and it still aggravates me. I may try adjusting the clutch and/or lever free play some more to see if it will help by maybe moving the point where resistance is felt. Still need to study the shop manual to see how the slipper clutch is designed and what adjustments may be available other than lever free play..

[smallj]

When I am ready for replacement tires I am going to try out the new Metzler M5. They have been given very good reviews.